Curable two-part coatings for conductors

ABSTRACT

A compositional kit for forming a composition includes a first composition and a second composition which are separate. The first composition includes a filler, a cross-linking agent and an emissivity agent; and the second composition includes a silicate binder. Methods for making a compositional kit and for making a coated overhead conductor are also provided.

REFERENCE TO RELATED APPLICATION

The present application claims the priority of U.S. provisionalapplication Ser. No. 62/010,144, entitled CURABLE TWO-PART COATINGS FORCONDUCTORS, filed Jun. 10, 2014, and U.S. application Ser. No.14/735,794, entitled CURABLE TWO-PART COATINGS FOR CONDUCTORS, filedJun. 10, 2015, and hereby incorporates the same applications herein byreference in their entirety.

TECHNICAL FIELD

The present disclosure relates to a surface modified overhead conductorhaving a coating that allows the conductor to operate at lowertemperatures.

BACKGROUND

As the need for electricity continues to grow, the need for highercapacity transmission and distribution lines grows as well. The amountof power a transmission line can deliver is dependent on thecurrent-carrying capacity (ampacity) of the line. The ampacity of aline, however, is limited by the maximum safe operating temperature ofthe bare conductor that carries the current. Exceeding this temperaturecan result in damage to the conductor or to the transmission anddistribution line accessories. The conductor temperature is determinedby the cumulative effect of heating and cooling on the line. Theconductor is heated by Ohmic losses and solar heat and cooled byconduction, convection and radiation. The amount of heat generated dueto Ohmic losses depends on the current (I) and the electrical resistance(R) of the conductor and is determined by the relationship that Ohmiclosses=I²R. Electrical resistance (R) itself is further dependent ontemperature. Higher current and temperature leads to higher electricalresistance, which, in turn, leads to greater electrical losses in theconductor.

Several solutions have been proposed in the art to create highercapacity transmission and distribution lines. For example, overheadconductors coated with spectrally selective surface coatings are known.Such coatings can have a coefficient of heat emission (E) higher than0.7 and coefficient of solar absorption (A) that is less than 0.3. Suchcoatings can be white in color to lower solar absorption.

Overhead cables having a black paint coating with an emissivity greaterthan 0.6 are also known. Such paints can be made of a plastic (e.g.polyurethane) and black color pigment.

Electric conductors coated with a polymeric layer whose emissivitycoefficient is 0.7 or more and solar absorption coefficient is 0.3 orless are also known. Such polymeric layer can be produced frompolyvinylidene fluoride (PVDF) and a white pigment additive.

However, many of these known coatings are white coatings that are notdesirable due to glare and discoloration which can occur over time.Furthermore, polymeric coatings are also not desirable due to theirquestionable heat and wet aging characteristics.

Heat protective coatings are also generally known. However, suchcoatings are used to protect a substrate from heat external to thesubstrate, and do not cool the substrate by radiating heat to theexternal environment.

Therefore, there remains a need for a durable, inorganic, coating foroverhead conductors that allow the conductors to operate at reducedtemperatures.

SUMMARY

In accordance with one embodiment, a method for making a compositionalkit to form a curable coating composition comprises mixing a firstcomposition and mixing a second composition, wherein the firstcomposition and the second composition are separated. The firstcomposition includes from about 2% to about 55% of a filler, by dryweight of the compositional kit, about 5% to about 20% of across-linking agent, by dry weight of the compositional kit, and about6% to about 42% of an emissivity agent, by dry weight of thecompositional kit. The second composition includes a metal silicatebinder. The metal of the metal silicate binder is one of an alkali earthmetal or an alkaline earth metal.

In accordance with another embodiment, a method for making an overheadconductor is provided. The method includes providing a composition kitby mixing a first composition and mixing a second composition, whereinthe first composition and the second composition are separated; thenmixing the first composition and the second composition together to forma coating composition, and then applying the coating composition on asurface of a bare conductor to form the overhead conductor. The firstcomposition includes from about 2% to about 55% of a filler, by dryweight of the compositional kit, about 5% to about 20% of across-linking agent, by dry weight of the compositional kit, and about6% to about 42% of an emissivity agent, by dry weight of thecompositional kit. The second composition includes about 20% to about65% of a metal silicate binder, by dry weight of the compositional kit.The metal of the metal silicate binder is one of an alkali earth metalor an alkaline earth metal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a cross-sectional view of a bare conductor having aplurality of core wires according to one embodiment.

FIG. 2 depicts a cross-sectional view of a bare conductor without corewires according to one embodiment.

FIG. 3 depicts a cross-sectional view of a bare conductor formed oftrapezoidal shaped conductive wires and having a plurality of core wiresaccording to one embodiment.

FIG. 4 depicts a cross-sectional view of a bare conductor formed fromtrapezoidal shaped conductive wires and without core wires according toone embodiment.

FIG. 5 depicts a continuous coating process for a conductor according toone embodiment.

FIG. 6 depicts a cross-sectional view of a flooded die according to oneembodiment.

FIG. 7 depicts a perspective view of the flooded die of FIG. 6.

FIG. 8 depicts a cut-away view of the flooded die of FIG. 6.

FIG. 9 depicts a test arrangement used to measure the temperature ofmetal substrates for a given applied current.

DETAILED DESCRIPTION

The temperature of a conductor is dependent on a number of factorsincluding the electrical properties of the conductor, the physicalproperties of the conductor, and the local weather conditions. Forexample, the temperature of a conductor can increase by absorbing heatfrom the sun due to solar radiation. The amount of heat absorbed isdependent on the surface of the conductor, that is, the surface'scoefficient of absorptivity (“absorptivity”). A low absorptivityindicates that the conductor absorbs only a small amount of heat due tosolar radiation.

A conductor can generally reduce its temperature by emitting heatthrough radiation. The amount of heat radiated is dependent on theconductor surface's coefficient of emissivity (“emissivity”). A highemissivity indicates that the conductor is radiating more heat than aconductor with a lower emissivity.

Accordingly, in certain embodiments, an overhead conductor that includesa heat radiating agent can, when tested in accordance to ANSIC119.4-2004, operate at a lower temperature than the temperature of thesame conductor without the heat radiating agent. The heat radiatingagent can be incorporated directly into the conductor or can be coatedon the conductor. In one embodiment, the operating temperature can bereduced by about 5° C. or more.

Additionally, methods for coating an overhead conductor with aninorganic, non-white, flexible coating that reduces the operatingtemperature of the conductor compared to the temperature of the sameconductor without the heat radiating agent are also described herein.

In certain embodiments, a coating layer placed on an overhead conductorcan have other beneficial properties including improvement in one ormore of the corrosion resistance of the conductor, the corona resistanceof the conductor, the lifespan of the conductor, and a reduction in iceand dust on the conductor.

In certain embodiments, a two-part coating composition (also referred toherein as a compositional kit) can, when coated on an overhead conductorand tested in accordance to ANSI C119.4-2004, reduce the operatingtemperature of the conductor compared to the temperature of the sameconductor without the heat radiating agent. In one embodiment, theoperating temperature can be reduced by about 5° C., or more, whencompared to the operating temperature of an uncoated overhead conductor,when the operating temperatures measured are about 60° C. or higher. Incertain embodiments, the operating temperature can be reduced by about10° C., or more, when compared to the operating temperature of anuncoated overhead conductor, when the operating temperatures measuredare about 100° C. or higher. As can be appreciated, a reduction inoperating temperature can allow for either thinner conductors to beutilized for a given current carrying capacity or for increased currentcarrying capacity to be used on traditionally sized conductors. Forexample, a cable coated with the two-part coating composition canoperate at a lower temperature while conducting 1900 amps than asimilar, uncoated, cable conducting only 1500 amps.

According to certain embodiments, a two-part coating composition orcompositional kit can include a first composition part including afiller, a cross-linking agent (e.g., reactive agent), and an emissivityagent; and a second composition part including a silicate binder. Thetwo-parts (e.g., the first and second composition parts) can be keptseparate until use. The inventors have unexpectedly discovered that uponmixing of the two parts, the resulting coating composition can bothbegin to cure and exhibit an increase in viscosity over time. Withoutbeing bound by any particular theory, it is theorized that the curingoccurs due to a reaction between the cross-linking agent and thesilicate binder. As can be appreciated, as the viscosity increases, theability of the coating composition to coat an overhead conductor becomesmore difficult. As such, it can be advantageous to keep the twocomposition parts separate until use.

As used herein, all percentages (%) are percent by weight of the totalcomposition, also expressed as weight/weight %, % (w/w), w/w, w/w % orsimply %, unless otherwise indicated. Also, as used herein, the terms“wet” refers to relative percentages of the coating composition in adispersion medium (e.g. water); and “dry” refers to the relativepercentages of the dry coating composition prior to the addition of thedispersion medium. In other words, the dry percentages are those presentwithout taking the dispersion medium into account. Wet admixture refersto the coating composition with the dispersion medium added. “Wet weightpercentage”, or the like, is the weight in a wet mixture; and “dryweight percentage”, or the like, is the weight percentage in a drycomposition without the dispersion medium. Unless otherwise indicated,percentages (%) used herein are dry weight percentages based on theweight of the total composition.

According to certain embodiments, a suitable filler for a firstcomposition can be a metal oxide, including, but not limited to, quartz,aluminum oxide, mica, calcined kaolin, wallastonite, calcite, zirconia,zircon, micacious iron oxide, iron oxide, aluminum silicates, talc(sometimes referred to as hydrated magnesium silicate), barium sulphate,lithopone, and combinations thereof. In certain embodiments, morespecific examples of a suitable filler can be selected from talc,calcined kaolin, aluminum oxide and/or quartz. In certain embodiments, asuitable filler can have an average particle size of about 50 microns orless, in certain embodiments, about 20 microns or less, and in certainembodiments, about 5 microns or less. The total amount of filler in acompositional kit can be about 2% to about 55%, in certain embodiments,about 10% to about 40%, and in certain embodiments about 15% to about30%.

According to certain embodiments, a suitable cross-linking agent (e.g.,reactive agent) can be a compound that when mixed with a binder,particularly in an aqueous slurry, can promote curing of thecomposition. Examples of suitable cross-linking agents can include, butare not limited to, magnesium hydroxide, magnesium oxide, zinc oxide, orcombinations thereof. In certain embodiments, specific examples of asuitable cross-linking agent can include magnesium hydroxide and/ormagnesium oxide. In certain embodiments, the total amount ofcross-linking agent present in a compositional kit can vary from about5% to about 20%, and in certain embodiments from about 7% to about 15%.

An emissivity agent can improve the ability of a composition to radiateheat from the overhead conductor. Examples of suitable emissivity agentscan include, but is not limited to, gallium oxide, cerium oxide,zirconium oxide, silicon hexaboride, carbon tetraboride, silicontetraboride, silicon carbide, molybdenum disilicide, tungstendisilicide, zirconium diboride, zinc oxide, cupric chromite, magnesiumoxide, silicon dioxide, chromium oxides, iron oxide, boron carbide,boron silicide, copper chromium oxide, titanium dioxide, aluminumnitride, boron nitride, alumina, and combinations thereof. In certainembodiments, specific examples of a suitable emissivity agent can beselected from boron oxide, cerium oxide, and/or titanium dioxide. Incertain embodiments, the total amount of emissivity agent in acompositional kit can be about 6% to about 42%, in certain embodiments,about 10% to about 32%, and in certain embodiments, about 15% to about28%.

A suitable silicate binder can be an alkali/alkaline earth metalsilicate, such as, but not limited to, potassium silicate, sodiumsilicate, lithium silicate, calcium silicate, or combinations thereof.In certain embodiments, a silicate binder can also be aqueous colloidalsilica. In certain embodiments, the binder can be potassium silicate. Incertain embodiments, a suitable metal silicate can also be provided asan aqueous solution. As can be appreciated by one skilled in the art, asuitable aqueous solution, such as a solution formed of potassiumsilicate and potassium oxide, can have, for example, a metal oxide tosilica ratio of about 1:1 to about 1:6 in certain embodiments, or aratio of about 1:2 to about 1:4 in certain embodiments. The silicatebinder can be present in a compositional kit at about 20% to about 65%,in certain embodiments at about 20% to about 50%, and in certainembodiments at about 25% to about 35%.

As can be appreciated, a compositional kit can additionally includeother additives including one or more of a stabilizer, a defoamer, andan emulsifier. Such additives can be added to either the firstcompositional part or the second compositional part of the compositionalkit. Examples of suitable stabilizers can include, but are not limitedto, bentonite, kaolin, magnesium alumina silica clay, and stabilizedzirconium oxide. Additionally, or alternatively, other ball claystabilizers can also be included as a suitable stabilizer. In certainembodiments, the stabilizer can be bentonite. The stabilizer can beadded at about 0.1% to about 2%.

A defoamer can be included to inhibit, or retard, the formation of foamwhen water is added to a dry composition. Suitable examples of defoamerscan include silicon-based antifoam agents and non-silicon-based antifoamagents. Certain surfactants can also be used as a defoamer. Examples ofsuch surfactants can include, but are not limited to, cationic, anionic,or non-ionic surfactants, and fatty acid salts. A defoamer can be addedat about 0.2% to about 1.5%.

An emulsifier can be included to maintain an even dispersion when wateris added to a dry composition. Suitable examples of emulsifiers caninclude sodium lauryl sulfate, sodium dodecyl phenylsulfonate, potassiumstearate, sodium dioctyl sulfosuccinate, dodecyl diphenyloxydisulphonate, ammonium nonyl phenoxyethyl poly(l) ethoxyethyl sulfate,sodium styryl sulfonate, sodium dodecyl allyl sulfosuccinate, linseedoil fatty acid, sodium or ammonium salt of ethoxylated nonylphenolphosphate, sodium octoxynol-3-sulfonate, sodium coconut creatinate,sodium 1-alkoxy-2-hydroxypropyl sulfonate, sodiumα-olefin(C₁₄-C₁₆)sulfonate, hydroxyl alkanol sulfate, tetra sodiumN-(1,2-dicarboxylethyl)-N-octadecyl sulfosalicyloyl amine salt,N-octadecyl sulfosalicyloyl amino-acid disodium salt, disodiumalkylamido polyethoxy sulfosuccinate, disodium ethoxylated nonylphenolsulfosuccinate half ester, sodium ethoxyethyl sulfate. The amount of theemulsifier used can be about 2% to about 3%.

A compositional kit can additionally include a plasticizer to improvethe flexibility of the coating layer after application to a substrate.Suitable examples of a plasticizer include one or more of glycerol,sugar, and cellulose.

In certain embodiments, the first composition part can include about 1%to about 18% talc, about 1% to about 15% calcined kaolin, about 0% toabout 10% aluminum oxide, about 0% to about 12% quartz, about 5% toabout 20% magnesium hydroxide and/or magnesium oxide, about 1-12% boronoxide, silicon carbide, and cerium oxide, and about 5% to about 30%titanium dioxide; and the second part contains about 20% to about 65%potassium silicate.

As can be appreciated, the first and second compositional parts can bemixed separately and can be kept separated until just prior to use. Thecomponents of the first compositional part can be mixed and then storeddry or wet. When wet, the dispersion medium can be water. The resultingfirst compositional part, as a wet mixture, can be a suspension with atotal solid content of about 30% to about 55%, in certain embodimentsabout 35% to about 50%, and in certain embodiments about 43% to about50%. Organic dispersants can also be used as the dispersion medium.Suitable examples of such organic dispersants can include, but are notlimited to, alcohols, ketones, esters, hydrocarbons, and combinationsthereof. In certain embodiments, the organic dispersants can be watermiscible. A wet second compositional part can similarly be prepared. Thesecond compositional part, as a wet mixture, can be a suspension with atotal solid content of about 20% to about 50%, in certain embodiments,about 25% to about 45%, and in certain embodiments about 30% to about38%. The two-parts of the compositional kit, whether dry or wet, shouldnot come into contact when stored. The compositional kit can begin tocure as soon as the two compositional parts are mixed. As a result ofthe curing process, the viscosity of the coating composition canincrease with time. Because high viscosity adversely affects the coatingcomposition as it is coated onto the bare conductor, the mixing of thefirst and second parts (compositions) can be delayed until just beforeapplication.

Upon mixing of the two compositional parts, the coating composition canbe used to coat a bare conductor. In certain embodiments, the coatingcomposition can be used within about 24 hours after mixing, in certainembodiments within about 12 hours, and in certain embodiments withinabout 8 hours. Upon mixing of the two parts in a wet mixture, theviscosity of the wet mixture can be from about 10 seconds to about 30seconds, in certain embodiments from about 13 seconds to about 25seconds, and in certain embodiments from about 15 seconds to about 20seconds as measured by using a B4 Ford cup in accordance to ASTM D1200(2010). Additionally, the viscosity of the wet mixture can increase nomore than 65% within about 8 hours of mixing the first and secondcompositional parts together. The wet mixture can be prepared in a HighSpeed Disperser (“HSD”), Ball Mill, Bead mill or using other techniquesknown in the art. As illustration, a HSD can be used to make the coatingcomposition be slowly added together the first and second compositionparts and mixing until the desired dispersion of the components isachieved. In certain embodiments, the mixer speed can be about 10 rpm ormore to achieve the desired coating composition.

Once applied and cured on a conductor, the coating can offer a flexiblecoating that shows no visible cracks when bent on a mandrel of diameterof about 5 inches or less. In certain embodiments, the flexible coatingcan show no visible cracks when bent on mandrel diameters ranging from0.5 inch to 5 inches. The cured coating can also be heat resistant andcan pass the same mandrel bend test after heat aging at 90° C. for 7days. The cured coating can also be exterior weather resistant and canpass the same mandrel bend test after 4,000 hours of exposure toexterior weathering condition (e.g. a combination of UV light, waterspray, and heat application).

A coating can be applied around a variety of cables including highvoltage overhead electricity transmission lines. As can be appreciated,such overhead electricity transmission lines can be formed in a varietyof configurations and can generally include a core formed from aplurality of conductive wires. For example, aluminum conductor steelreinforced (“ACSR”) cables, aluminum conductor steel supported (“ACSS”)cables, aluminum conductor composite core (“ACCC”) cables and allaluminum alloy conductor (“AAAC”) cables. ACSR cables are high-strengthstranded conductors and include outer conductive strands, and supportivecenter strands. The outer conductive strands can be formed fromhigh-purity aluminum alloys having a high conductivity and low weight.The center supportive strands can be steel and can have the strengthrequired to support the more ductile outer conductive strands. ACSRcables can have an overall high tensile strength. ACSS cables areconcentric-lay-stranded cables and include a central core of steelaround which is stranded one, or more, layers of aluminum, or aluminumalloy, wires. ACCC cables, in contrast, are reinforced by a central coreformed from one, or more, of carbon, glass fiber, aluminum oxide fiberor polymer materials. A composite core can offer a variety of advantagesover an all-aluminum or steel-reinforced conventional cable as thecomposite core's combination of high tensile strength and low thermalsag enables longer spans. ACCC cables can enable new lines to be builtwith fewer supporting structures. AAAC cables are made with aluminum oraluminum alloy wires. AAAC cables can have a better corrosionresistance, due to the fact that they are largely, or completely,aluminum. ACSR, ACSS, ACCC, and AAAC cables can be used as overheadcables for overhead distribution and transmission lines.

As can be appreciated, a cable can also be a gap conductor. A gapconductor can be a cable formed of trapezoidal shaped temperatureresistant aluminum zirconium wires surrounding a high strength steelcore.

FIGS. 1, 2, 3, and 4 each illustrate various bare overhead conductorsaccording to certain embodiments. Overhead conductors 100, 200, 300 and400 can generally include only one or more conductive wires 210 and 410like in FIGS. 2 and 4, or conductive wires 120, 210, 320 and 410surrounding the cores 110 and 310 like in FIGS. 1 and 3. Each overheadconductor depicted in FIGS. 1-4 can include a coating (130, 220, 330 and420) formed from the two compositional parts. Additionally, FIGS. 1 and3 can, in certain embodiments, be formed as ACSR cables throughselection of steel for the core and aluminum for the conductive wires.Likewise, FIGS. 2 and 4 can, in certain embodiments, be formed as AAACcables through appropriate selection of aluminum or aluminum alloy forthe conductive wires.

In alternate embodiments the cores 110, 310 can be steel, invar steel,composite materials, any other material that can provide strength to theconductor. In other alternate embodiments the conductive wires 120, 210,320, 410 can be made of any suitable conductive material includingcopper, a copper alloy, aluminum, an aluminum alloy, including aluminumtypes 1350, 6000 series alloy aluminum, aluminum-zirconium alloy, carbonnanotube, grapheme, or any other conductive material.

Composite core conductors are useful due to having lower sag at higheroperating temperatures and their higher strength to weight ratio.Composite materials are based on glass fiber, carbon fiber, polymericfibers, aluminum oxide fiber reinforced in aluminum or any othermaterial that can provide strength and lower sag to the conductor. Apolymeric coating can also, or alternatively, be utilized in compositecore conductor designs. As can be appreciated, a composite coreconductor with the coating formed from a compositional kit can have afurther reduction in conductor operating temperatures due to the coatingand can have both a lower sag and lower degradation of certain polymerresins in the composite from the lowered operating temperatures.Non-limiting examples of composite cores can be found in U.S. Pat. No.7,015,395, U.S. Pat. No. 7,438,971, U.S. Pat. No. 7,752,754, U.S. PatentApp. No. 2012/0186851, U.S. Pat. No. 8,371,028, U.S. Pat. No. 7,683,262,and U.S. Patent App. No. 2012/0261158, each of which are incorporatedherein by reference.

In certain embodiments, the surface of the overhead conductor can beprepared prior to the application of the coating composition. Thepreparation process can include one or more of chemical treatment,pressurized air cleaning, hot water or steam cleaning, brush cleaning,heat treatment, sand blasting, ultrasound, deglaring, solvent wipe,plasma treatment, and the like. In certain processes, the surface of theoverhead conductor can be deglared by sand blasting.

According to certain embodiments, a coating composition can be appliedby spray gun at about 10 psi to about 45 psi pressure using controlledair pressure. In such embodiments, the spray gun nozzle can be placedperpendicular to the direction of the conductor (e.g., an approximately90° angle) to get a uniform coating on conductor product. In certaincases, two or more guns can also be used to get more efficient coatings.The coating thickness and density are controlled by the admixtureviscosity, gun pressure, and conductor line speed. During the coatingapplication, the overhead conductor temperature can be maintainedbetween 10° C. to 90° C. depending on the material of the conductor.

Alternatively, in certain embodiments, a coating composition can beapplied to an overhead conductor by one or more of dipping, a brush, orby roller. For example, in a dipping process, a cleaned and driedconductor can be dipped into a coating composition to allow the coatingcomposition to completely coat the conductor. The conductor can then beremoved from the coating composition and allowed to dry.

After application of the coating, the coating on the overhead conductorcan be allowed to cure/dry by evaporation either at room temperature orat elevated temperatures. In certain embodiments, a coating can be driedby oven heating. In certain such embodiments, the oven can be about 325°C., in certain embodiments from about 200° C. to about 250° C. Incertain embodiments, a coating can also, or alternatively, be subjectedto direct flame exposure which exposes the coating to intense heating.For example, in certain embodiments, direct flame can be applied forabout 0.1 seconds to about 60 seconds, and in certain embodiments fromabout 0.5 seconds to about 30 seconds. In yet a further embodiment, thecable can be oven heated, followed by direct flame exposure. Here, thetwo heating processes can take place: continuously online, i.e, thecable can exit the oven and can then lead directly to the flame or,alternatively, can take place in a batch manner. For example, after ovenheating, a cable can be wound on to a bobbin, which can then betransferred to a flaming apparatus where the cable is unwound from thebobbin and run through a flame to further cure/dry the coating. Incertain embodiments, after being oven and flame heated, a cable can bewould on a bobbin which can be further heated in an oven. In suchembodiments, the oven can be about 200° C. to about 325° C. in certainembodiments, and at about 200° C. to about 250° C. in certainembodiments. The bobbin can be heated in the oven for about 0.1 hour toabout 24 hours in certain embodiments, and for about 1 hour to about 15hours, in certain embodiments.

As can be appreciated, a coating can also be applied to conductors whichare already installed and are currently in use. Existing conductors canbe coated with a robotic system for automated or semi-automated coating.The automated system functions in three steps: (1) cleaning theconductor surface; (2) applying the coating on the conductor surface;and (3) drying the coating.

Additionally, a coating can be applied to overhead transmission lineaccessories. For example, a substation can include a variety ofaccessories that generate heat including a breaker and a transformersuch as a current coupling transformer. The coating described herein canbe applied to one or more of these accessories to reduce the operatingtemperature of the coated accessory compared to a similar, but uncoated,accessory. As can be appreciated, additional transmission lineaccessories can also benefit from such a coating including, asnon-limiting examples, deadends/termination products, splices/joints,suspension and support products, motion control/vibration products(sometimes referred to as dampers), guying products, wildlife protectionand deterrent products, conductor and compression fitting repair parts,substation products, clamps, and corona rings. A coating can be appliedto such accessories in any suitable manner. For example, a coating canbe applied to a new accessory after cleaning the accessory's surface.Alternatively, a coating can also be applied to an existing accessoryafter cleaning the accessory's surface. In each such embodiment, thecoating can be dried and cured by exposure to ambient temperatures orelevated temperatures provided by, for example, a direct flame.

A coating can be applied to a conductor in several ways. For example, acoating can be applied by coating the individual wires before theirassembly in the bare overhead conductor. As can be appreciated, it ispossible to coat all of the wires of the conductor, or, moreeconomically, coat only the outer most wires of a conductor.Alternatively, a coating can be applied only to the outer surface of thebare overhead conductor instead of the individual wires. In certainembodiments, the complete outer surface of a bare conductor can becoated. In other embodiments, only a portion of the bare conductor canbe coated.

As can be appreciated, a coating can be applied in a batch process, asemi-batch process, or a continuous process. FIG. 5 illustrates acontinuous coating process and depicts a conductor 512 passing from anintake winding roll 502 to a pretreatment unit 504 and coating unit 506.The pretreatment unit 504 prepares the surface of the conductor forapplication of the coating in the coating unit 506. After the coating isapplied, the conductor can be dried via a drying/curing unit 508. Oncedried, the cable can be wound on a roller 511.

In the pretreatment unit 504, the surface of the conductor 512 can beprepared by media blasting. Such media can include sand, glass beads,ilmenite, steel shot, and other suitable media. The media blasting canbe followed by air-wiping to blow the particulate materials off theconductor 512. An air-wipe uses jets to blow air on to the conductor 512at an angle and in a direction opposing the direction of travel of theconductor 112. The air jets create a 360° ring of air that attaches tothe circumference of the conductor 512 and wipes the surface with thehigh velocity of air. In such an example, as the conductor exits thepretreatment unit 504, any particles adhered to the conductor 512 can bewiped and blown back into the pretreatment unit 504. A suitable air jetcan operate at about 60 to about 100 PSI, in certain embodiments, atabout 70 PSI to about 90 PSI in certain embodiments, and at about 80 PSIin certain embodiments. The air jet can have a velocity (coming out ofthe nozzles) of about 125 mph to about 500 mph in certain embodiments,about 150 mph to about 400 mph in certain embodiments, and about 250 mphto about 350 mph in certain embodiments. After the air-wipe, the numberof particles that are greater than about 10 microns in size remaining onthe surface of the conductor can be about 1,000 particles per squarefeet, or less, in certain embodiments, or about 100 particles per squarefeet, or less, in certain embodiments. After the air wipe, the conductorcan be heated, e.g. by a heating oven, UV, IR, E-beam, inductionheating, pressurized steam heating, open flame, and the like. Theheating can be accomplished by single or multiple units. In oneembodiment, the direct flame application can be used for preheating theconductor. Here, the cable can be passed directly through a flame toheat the cable surface to a temperature above ambient temperature. Ahigh heating temperature in pretreatment can allow for a lower heatingtemperature to be utilized in the drying/curing unit. However, heatingshould not be too severe that it affects the quality of the coating(e.g. through adherence, evenness, blistering etc). In certainembodiments, the conductor 512 should not be heated above about 140° C.,and in certain embodiments to no more than about 120° C.

Once the surface of the conductor 512 is prepared, it can be ready forcoating. The coating process can take place in the coating unit wherethe cable passes through a flooded die that deposits a liquid suspensionof the coating composition onto the prepared surface. FIGS. 6 to 8depict an annular shaped flooded die 601. The coating suspension can befed to the die 601 via a tube 606. As the conductor 512 passes thoughthe center opening 604 of the flooded die 601, the coating compositioncoats the conductor 512 via one or more opening ports 602 in the innersurface of the die 601. In certain embodiments, the flooded die 601 caninclude two or more, four or more, or six or more, opening ports 602evenly spaced around the circumference of the inner surface. Once theconductor 512 exits the flooded die, the conductor 512 can pass throughanother air wipe to remove excess coating suspension and to spread thecoating composition evenly around the conductor. In the case of astranded conductor, the air wipe can allow the coating to penetrate thegrooves between the strands on the surface of the conductor. This airwipe can operate using similar conditions as the air wipe in thepretreatment unit 504.

Once the conductor 512 is coated, it can pass through the drying/curingunit 508, as depicted in FIG. 5. Drying/curing can be accomplished byusing air or heated air. For example, suitable air can be heated toabout 1000° C. in certain embodiments and the drying/curing unit canoperate with a line speed from about 9 feet/min to about 500 feet/min incertain embodiments, and a line speed of about 10 feet/min to about 400feet/min in certain embodiments. The temperature of the air and the linespeed can be selected based on the metal alloy used in the conductor512. The drying process can be a gradual drying process, a rapid dryingprocess, and/or a direct flame application process. As can beappreciated, drying or curing can also be accomplished by othertechniques, including the use of one or more of a heating oven, UVradiation, IR radiation, E-beam curing, induction heating, chemicalapplication, carbon dioxide gas or liquid spray and the like. The dryingprocess can occur in a single unit or occur in multiple units. It canalso be vertical or horizontal or occur at a specific angle. In certainembodiments, the drying/curing can occur by heating, followed by directflame application. For example, a cable can first pass through a heatingoven, and then directly through a flame to heat the cable surface to atemperature of about 150° C. or less, and in certain embodiments, to atemperature of about 120° C. or less. Once dried or cured, the coatedconductor can be wound on a roller 511 for storage.

The continuous process, if operated for an individual strand (instead ofa stranded cable), can operate at a line speed of about 2500 ft/min orless in certain embodiments, from about 9 ft/min to about 2000 ft/min incertain embodiments, from about 10 ft/min to about 500 ft/min in certainembodiments, and from about 30 ft/min to about 300 ft/min in certainembodiments.

Once coated onto a conductor 512 and dried/cured, the coating layer canbe less than about 100 microns in certain embodiments, and in certainembodiments about 10-30 microns. The coatings produced can be non-whitehaving a L value of about 20 or more. The coatings can be electricallynon-conductive, semi-conductive, or conductive.

The coated conductor can exhibit improved heat dissipation. Emissivityis the relative power of a surface to emit heat by radiation, and theratio of the radiant energy emitted by a surface to the radiant energyemitted by a blackbody at the same temperature. Emittance is the energyradiated by the surface of a body per unit area. Emissivity can bemeasured, for example, by the method disclosed in U.S. PatentApplication Publication No. 2010/0076719 to Lawry et al., which isincorporated herein by reference. The coated conductor can have anemissivity coefficient of about 0.3 or more in certain embodiments, incertain embodiments, about 0.5 or more, and in certain embodiments about0.75 or more.

Without further description, it is believed that one of ordinary skillin the art can, using the preceding description and the followingillustrative examples, make and utilize the compositions and methods ofthe present disclosure. The following examples are given to illustratethe present disclosure and claimed invention. It should be understoodthat the disclosure and claimed invention is not to be limited to thespecific conditions or details described in those examples.

EXAMPLES Testing Procedures

Viscosity:

Viscosity of the compositions were measured using B4 ford cupviscometers in accordance to ASTM D 1200 (2010).

Tape Adhesion:

Tape adhesion tests were performed on coated aluminum strip inaccordance to ASTM D 3359 (2009).

Coating Applicability:

To determine coating applicability, two coating defects, pinhole defectsand dry spot defects, were evaluated on coated samples. The number ofthese defects per square centimeter of coated strip was determined. Sixor more coating defects per square centimeter indicated “poor”applicability; two to five defects per square centimeter indicated“medium” applicability; and one or no defects indicated “good”applicability. Compositions having “medium” or “good” applicability wereconsidered acceptable for coating purposes.

Mandrel Bend Test:

The flexibility of the coating was tested using the Mandrel Bend test.In the Mandrel Bend test, coated samples are bent on differentcylindrical mandrels sizes (from larger diameter to small diameter) toobserve the coatings for any visible cracks. The presence of visiblecracks indicates failure of the sample.

Heat Aging:

To study thermal stability of the coating, coated samples were placed inan air circulation oven at a temperature of 90° C. for a period of 7days. After the thermal aging was complete, the samples were placed atroom temperature for a period of 24 hrs. The samples were then bent ondifferent cylindrical mandrels sizes (from larger diameter to smalldiameter) and inspected for any visible cracks at each of the mandrelsizes.

Water Aging Test:

To study the hot water stability of the coating, coated samples wereaged in a hot water bath maintained at 90° C. for 7 days. After theaging process was complete, the samples were removed and allowed tostand at room temperature for a period of 24 hours before testing. Theaged samples were then tested by bending the samples on a series ofmandrels of decreasing cylindrical size and inspected for any visiblecracks at each of the mandrel sizes. The samples were also weighedbefore and after aging to determine any weight gain/loss from theboiling water aging.

Temperature Reduction:

Testing was conducted to measure the effectiveness of the coating toreduce operating temperature of conductor samples in accordance with theCurrent Cycle Test Method, ANSI C119.4-2004, except that the test wasperformed for a reduced number of heat cycles (at least fifty cycleswere performed). An experimental set-up is prepared as depicted in FIG.9 and is described below.

As depicted in FIG. 9, a series loop was formed with six identicallysized four foot conductor specimens (three uncoated and three coated),and an additional suitable conductor routed through the currenttransformer. The series loop consisted of two runs of three identicallysized conductor specimens. The bare and coated conductor specimens werewelded in an alternating fashion. An equalizer was installed betweenconductor specimens to provide equipotential planes for resistancemeasurements. The equalizers ensured permanent contacts between allconductor strands. Equalizers (2″×⅜″×1.75″ for 2/0 solid aluminium and3″×⅜″×3.5″ for 795 AAC Arbutus) were fabricated from aluminium bus.Holes in a size of the connecting conductor were drilled into theequalizers. Ends of the adjacent conductors were welded to theequalizers to complete the series loop. A larger equalizer (10″×⅜″×1.75″for 2/0 solid aluminium and 12″×⅜″×3.5″ for 795 AAC Arbutus) was used atone end to connect the two runs, while the other end was connected to anadditional conductor routed through the current transformer.

Emissivity and Solar Absorptivity:

Emissivity and solar absorptivity of the coated and uncoated sampleswere measured in accordance to ASTM E408 (2013) and ASTM E903 (2012),respectively.

Weathering Test:

Samples were weathered in accordance to ASTM G155-05a (2013) by placingthe samples in a chamber and cycling the exposed samples to light,moisture, and heat. Each cycle was 120 minutes and included 102 minutesof light from a daylight filtered xenon-arc lamp at 63° C., and 18minutes of light and water spray. Samples were exposed for up to 10,000hours and removed every 2,000 hours for testing.

Salt Spray Test:

Salt spray testing was performed in accordance to ASTM 5117-11/ISO-10289. One foot samples of ASCR conductor were used. Thesamples were exposed to a salt solution of 5% NaCl in a salt spraychamber and observed daily for the appearance of rust, corrosion, or anyother visible change.

Examples

Three (3) coating compositions were produced and tested for viscosity,coating applicability, and tape adhesion. Details of the three coatingcompositions (Comparative Example 1 and Inventive Examples 1 and 2) areprovided on a dry weight basis and listed in Table 1. Test results arealso provided for each of Comparative Example 1 and Inventive Examples 1and 2 and reported in Table 1.

TABLE 1 Details of three coating compositions. Comparative InventiveInventive Components Supplier/Grade Example 1 Example 1 Example 2 Part 1Titanium Du Pont/Ti-Pure 12.5 12.5 12.5 dioxide R-706 grade MagnesiumYogi Dyechem 0 15 7.5 oxide Industries, India Calcined 20 Microns, 5 5 5kaolin India/Glazex grade Talc 20 Microns, 2 2 2 India/AR grade BoronBoron Carbide, 3 3 3 Carbide India/Vajrabor grade Quartz Dinesh Minerals17.5 2.5 30 powder (P) Ltd, India Part 2 Potassium Noble Alchem, 60 6040 silicate India Total 100 100 100 Properties Viscosity B4 17 18 15Ford cup (Sec) Coating Poor Good Medium applicability Tape adhesion PoorMedium Medium

The viscosity of Inventive Example 1 was tested over time after the twoparts were mixed together. The increased viscosity over time is shown inTable 2.

TABLE 2 Viscosity increase with time for Inventive Example 1. TIMEViscosity Bend test (½″ Boiling Coating (hours) (B4 Ford Cup) mandrelsize) water test applicability 0 18 sec passes passes Good 2 21 secpasses passes Good 4 21 sec passes passes Good 6 24 sec passes passesGood 8 28 sec passes passes Good 10 30 sec fails — Medium 17 55 secfails — Medium

Inventive Example 1 was used as a coating composition for overheadconductor cables. The cables were evaluated for various propertiesincluding temperature reduction, emissivity, and solar absorptivity. Thetest results comparing the coated and uncoated substrates are presentedin Table 3.

TABLE 3 Comparison of properties for coated and uncoated samples.Uncoated Coated Sample (using Sample Inventive Example 1) Temperature(95 A at 15 min.) 102.3 84.3 (° C.) for 2/0 solid aluminum TemperatureReduction (%) N/A −17.6 Salt Spray (after 1,500 hours) N/A No rust,flaking, chipping of sample observed Emissivity 0.16 0.86 SolarAbsorptivity 0.29 0.55

Inventive Example 1 was also used to prepare additional samples forevaluation with the Mandrel Bend test. Test results comparing a coatedsample and an uncoated sample are depicted in Table 4. Passing resultson the Mandrel Bend test means that no flaking, damage, or removal ofthe coating was observed.

TABLE 4 Mandrel Bend test before and after aging Uncoated Coated Sample(Using Sample Inventive Example 1) No aging N/A Passed ½″ Mandrel Bendtest Heat aging N/A Passed ½″ Mandrel Bend test (90° C. for 7 days)Weathering test N/A Passed ½″ Mandrel Bend test (after 10,000 hours)Water aging N/A Passed 1″ Mandrel Bend test (90° C. for 7 days) withless than a 1% weight increase

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue.

It should be understood that every maximum numerical limitation giventhroughout this specification includes every lower numerical limitation,as if such lower numerical limitations were expressly written herein.Every minimum numerical limitation given throughout this specificationwill include every higher numerical limitation, as if such highernumerical limitations were expressly written herein. Every numericalrange given throughout this specification will include every narrowernumerical range that falls within such broader numerical range, as ifsuch narrower numerical ranges were all expressly written herein.

Every document cited herein, including any cross-referenced or relatedpatent or application, is hereby incorporated herein by reference in itsentirety unless expressly excluded or otherwise limited. The citation ofany document is not an admission that it is prior art with respect toany invention disclosed or claimed herein or that it alone, or in anycombination with any other reference or references, teaches, suggests,or discloses any such invention. Further, to the extent that any meaningor definition of a term in this document conflicts with any meaning ordefinition of the same term in a document incorporated by reference, themeaning or definition assigned to that term in the document shallgovern.

The foregoing description of embodiments and examples has been presentedfor purposes of description. It is not intended to be exhaustive orlimiting to the forms described. Numerous modifications are possible inlight of the above teachings. Some of those modifications have beendiscussed and others will be understood by those skilled in the art. Theembodiments were chosen and described for illustration of variousembodiments. The scope is, of course, not limited to the examples orembodiments set forth herein, but can be employed in any number ofapplications and equivalent articles by those of ordinary skill in theart. Rather it is hereby intended the scope be defined by the claimsappended hereto.

What is claimed is:
 1. A method of making a compositional kit to form acurable coating composition, the method comprising: a. mixing a firstcomposition, the first composition comprising from about 2% to about 55%of a filler, by dry weight of the compositional kit, about 5% to about20% of a cross-linking agent, by dry weight of the compositional kit,and about 6% to about 42% of an emissivity agent, by dry weight of thecompositional kit; and b. mixing a second composition, the secondcomposition comprising about 20% to about 65%, by dry weight of thecompositional kit, of a metal silicate binder, wherein the metal of themetal silicate binder is one of an alkali earth metal or an alkalineearth metal; and wherein the first composition and the secondcomposition are separated.
 2. The method of claim 1, wherein the fillerhas an average particle size of about 50 microns or less and comprisesone or more of quartz, aluminum oxide, mica, calcined kaolin,wallastonite, calcite, zirconia, zircon, micacious iron oxide, ironoxide, aluminum silicates, talc, barium sulphate, and lithopone.
 3. Themethod of claim 1, wherein the crosslinking agent comprises one or moreof magnesium hydroxide, magnesium oxide, and zinc oxide.
 4. The methodof claim 1, wherein the emissivity agent comprises one or more ofgallium oxide, cerium oxide, zirconium oxide, silicon hexaboride, carbontetraboride, silicon tetraboride, silicon carbide, molybdenumdisilicide, tungsten disilicide, zirconium diboride, zinc oxide, cupricchromite, silicon dioxide, manganese oxide, chromium oxide, iron oxide,boron carbide, boron silicide, copper chromium oxide, titanium dioxide,aluminum nitride, boron nitride, alumina, and magnesium oxide.
 5. Themethod of claim 1, wherein the metal silicate binder comprises one ormore of potassium silicate, sodium silicate, lithium silicate, calciumsilicate, and magnesium aluminum silicate.
 6. The method of claim 1,wherein i) the filler comprises about 1% to about 18% talc, about 1% toabout 15% calcined kaolin, about 0% to about 10% aluminum oxide, andabout 0% to about 12% quartz; ii) the crosslinking agent comprises about5% to about 20% of one or more of magnesium hydroxide and magnesiumoxide; iii) the emissivity agent comprises about 1% to about 12% of oneor more of boron oxide, silicon carbide, and cerium oxide; and about 5%to about 30% titanium dioxide; and iv) the metal silicate bindercomprises about 20% to about 65% potassium silicate.
 7. The method ofclaim 1, wherein at least one of the first composition and the secondcomposition further comprises one or more of a stabilizer, anemulsifier, and a defoamer.
 8. The method of claim 1, further comprisingthe addition of water to at least one of the first composition and thesecond composition and mixing the water to form a wet admixture.
 9. Themethod of claim 8, wherein water is added to the first composition andthe second composition and wherein the first composition has a totalsolids content range of about 30% to about 55% and the secondcomposition has a total solids content range of about 20% to about 50%.10. The method of claim 1, further comprising: mixing the firstcomposition and the second composition together to form the curablecoating composition; applying the curable coating composition to asubstrate to form a coated surface; and drying the curable coatingcomposition with heat.
 11. A method for making a coated overheadconductor, the method comprising: a. providing a compositional kit byforming a first composition and a second composition; i. mixing thefirst composition comprising from about 2% to about 55% of a filler, bydry weight of the compositional kit, about 5% to about 20% of across-linking agent, by dry weight of the compositional kit, and about6% to about 42% of an emissivity agent, by dry weight of thecompositional kit; and ii. mixing a second composition comprising about20% to about 65% of a metal silicate binder, by dry weight of thecompositional kit, wherein the metal of the metal silicate binder is oneof an alkali earth metal or an alkaline earth metal and wherein thefirst composition and the second composition are mixed separately; b.mixing the first composition and second composition together to form acoating composition; and c. applying the coating composition on asurface of a bare conductor to form a coated overhead conductor.
 12. Themethod of claim 11, wherein a viscosity of the coating compositionincreases about 65% or more within about 8 hours of mixing the firstcomposition and second composition together.
 13. The method of claim 11,further comprising preparing the bare conductor before applying thecoating composition by sand blasting the conductor.
 14. The method ofclaim 11, wherein the coating composition is applied with a flooded die.15. The method of claim 11, further comprising curing the coatingcomposition with heat.
 16. The method of claim 11, wherein the coatedoverhead conductor has an operating temperature that is reduced by about10° C. or more when compared to the operating temperature of an uncoatedoverhead conductor, when the operating temperatures are measured atabout 100° C. or higher.
 17. The method of claim 11, wherein the coatedoverhead conductor comprises an emissivity coefficient of about 0.75 ormore.
 18. The method of claim 11, wherein the coating composition on thecoated overhead conductor comprises a thickness of about 10 microns toabout 30 microns.
 19. The method of claim 11, wherein the coatingcomposition has a L value of about 20 or more.
 20. The method of claim11, wherein the coated overhead conductor passes, both before and afteraging at 90° C. for 7 days, a mandrel bend test at mandrel diametersranging from 0.5 inch to 5 inches.